#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; namespace { using Integer = long long; //__int128; template istream& operator >> (istream& is, pair& p){return is >> p.first >> p.second;} template istream& operator >> (istream& is, vector& vec){for(T& val: vec) is >> val; return is;} template istream& operator , (istream& is, T& val){ return is >> val;} template ostream& operator << (ostream& os, const pair& p){return os << p.first << " " << p.second;} template ostream& operator << (ostream& os, const vector& vec){for(size_t i=0; i ostream& operator , (ostream& os, const T& val){ return os << " " << val;} template void print(const H& head){ cout << head; } template void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); } template void println(const T& ... values){ print(values...); cout << endl; } template void eprint(const H& head){ cerr << head; } template void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); } template void eprintln(const T& ... values){ eprint(values...); cerr << endl; } class range{ Integer start_, end_, step_; public: struct range_iterator{ Integer val, step_; range_iterator(Integer v, Integer step) : val(v), step_(step) {} Integer operator * (){return val;} void operator ++ (){val += step_;} bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;} }; range(Integer len) : start_(0), end_(len), step_(1) {} range(Integer start, Integer end) : start_(start), end_(end), step_(1) {} range(Integer start, Integer end, Integer step) : start_(start), end_(end), step_(step) {} range_iterator begin(){ return range_iterator(start_, step_); } range_iterator end(){ return range_iterator( end_, step_); } }; inline string operator "" _s (const char* str, size_t size){ return move(string(str)); } constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);} constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);} constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); } inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed mt19937 mt(chrono::duration_cast(chrono::steady_clock::now().time_since_epoch()).count()); template string join(const vector& v, const string& sep){ stringstream ss; for(size_t i=0; i0) ss << sep; ss << v[i]; } return ss.str(); } inline string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; } } constexpr long long mod = 9_ten + 7; class combination_mod{ const long long mod; const long long size; vector fact; //n! vector fact_inv; // (n!)^-1 void make_fact(){ fact[0] = 1; for(long long i=1; i> n; vector a(3); cin >> a; combination_mod cmb(mod, 3001); long long ans = 0; for(int two=0; two*3-1 <= n; two++){ for(int r_=0; r_<=a[0]; r_++){ int gb = two - r_; if( gb < 0) continue; if( gb > a[1] || gb > a[2] ) continue; int gb_solo = a[1]+a[2] - gb*2 - r_; if(gb_solo < 0) continue; int r_solo = a[0] - r_; int len = two * 3 + (gb_solo+r_solo) * 2; if(len-1 > n) continue; int emp = n+1 - len; long long k = r_+gb + gb_solo + r_solo + emp; int g_ = a[1] - gb; long long tmp = cmb(k,r_); k -= r_; (tmp *= cmb(k,gb)) %= mod; k -= gb; (tmp *= cmb(k,gb_solo)) %= mod; k -= gb_solo; (tmp *= cmb(k,r_solo)) %= mod; k -= r_solo; tmp *= my_pow_mod(2, two, mod); tmp %= mod; tmp *= cmb(gb_solo+r_,g_); tmp %= mod; (ans += tmp) %= mod; } } println(ans); return 0; }